1. Field of the Invention
The present invention relates to a method and test kit for determining the presence of a hydroxy substituted aromatic compound in a solution using titanium films which change light absorbance in the presence of the compound. In particular, the present invention relates to the use of preferred films prepared from a titanium alkoxide and an aliphatic carboxylic acid.
2. Prior Art
The polymerization of titanium alkoxide results from the hydrolysis of alkoxide groups as shown in equation (1). EQU M--OR+H.sub.2 O.fwdarw.M--OH+ROH (1)
Propagation occurs by subsequent polycondensation reactions. Two competitive mechanisms are possible during the polycondensation; they are olation and oxolation reactions. Olation is the formation of hydroxy bridges through the elimination of solvent molecules, EQU M--OH+MOHX.fwdarw.M--OH--M+XOH (X.dbd.H or alkyl group) (2)
and, oxolation is the formation of oxygen bridges through the elimination of H.sub.2 O or ROH, EQU M--OH+MOX.fwdarw.M--0--M+XOH (X.dbd.H or alkyl group) (3)
These reactions result in the transformation of the titanium alkoxide into the titanium oxide network. The contribution of each reaction determines the structure and morphology of the titanium oxide network.
The reaction of carboxylic acid with titanium alkoxide has been used to prepare titanium alkoxide precursors (Sanchez, C., et al., J. Non-Cryst. Solids 100, 65 (1988); Sanchez, C., et al., New J. Chem. 14, 513 (1990); and Sanchez, C., et al., in "Ultrastructure Processing of Advance Ceramics", Mackenzie, J. D.,; Ulrich, D. R. Eds, Wiley, N.Y. P. 77 (1988)). Changes in the titanium alkoxide precursors modify the hydrolysis and polycondensation reactions of the titanium alkoxide (Doeuff, S., et al., J. Non-Cryst. Solids 89, 206 (1987)). There are several U.S. patents on the preparation of polymeric titanium complexes with carboxylic acids (U.S. Pat. No. 2,621,193 (Dec. 9, 1952) to Langkammerer; U.S. Pat. No. 2,621,194 (Dec. 9, 1952; and U.S. Pat. No. 2,621,195 (Dec. 9, 1952) to Haslam). Titanium oxide gels (Gagliardi, C. D., et al., Mat. Res. Soc. Symp. Proc., 155, 127 (1989); and Livage, J., Mat. Res. Soc. Symp. Proc. 73, 717 (1986)) and films (Gagliardi, C. D., et al., Mat. Res. Soc. Symp. Proc., 180, 801 (1990)) have also been prepared by the controlled hydrolysis of the titanium alkoxide carboxylic acid precursors. The actual titanium oxide network has not been fully characterized. It is possible that the titanium oxide network may still undergo further reactions.
Color development is observed with titanium phenoxy complexes. For example dichlorodiphenoxytitanium (IV) (Watenpaugh, K., et al., Inorg. Chem. 5, 1782 (1966)) is red, tetraphenoxytitanium (IV) monophenolate ((a) Svetich, G. W., et al., J. Am. Chem. Soc. Chem. Commun., 676 (1971); (b) Svetich, G. W., et al., Acata Cryst. B28, 1760 (1972); and (c) Malhotra, K. C., et al., J. Organomet. Chem., 239, 159 (1982)) is an orange-red, isoproyltriphenoxy-titanium (IV) is a bright yellow (Varma, I. D., et al., J. Indian, Chem. Soc., 38, 147 (1961)), and [NH.sub.4 ].sub.2 [Ti(catecholate).sub.3)].2H.sub.2 O.sup.14 is a rust color. U.S. Pat. No. 4,043,820 to Landau discloses using titanium-catechol chelate to develop color when applied as an ink to alkaline paper (U.S. Pat. No. 4,043,820 (Aug. 23, 1977) to Landau). Such complexations are well established in the liquid phase where coordination sites to the titanium IV are easily accessible but no such chelation has been reported when Ti(IV) ions are immobilized in a solid network.
There is a need for a simple, reliable method for the detection of phenolic compounds, particularly in the field when testing water sources for the presence of such contaminants. The prior art has used sophisticated instrumentation such as gas chromatograph or mass spectrograph for this purpose; however, the use of such instrumentation in the field produces unreliable results and is expensive.